Shaft Rotating Device

ABSTRACT

A shaft rotating device for rotating a shaft of a medical instrument about its longitudinal axis relative to a handle of the medical instrument comprises an operating element for rotating the shaft. The operating element is arranged at a proximal portion of the shaft and it is in driving connection with the shaft such that the shaft is rotatable relative to the handle against frictional forces. The shaft rotating device further comprises a frictional element with a surface. The surface of the frictional element is in frictional contact with the surface of a counterpart for keeping the shaft and the handle rotationally stationary with respect to each other and movable against the frictional forces. The operating element and the frictional element are in operational connection with respect to one another such that a torque applied to the operating element decreases the frictional forces. The shaft and the frictional element are in operational connection with one another such that a torque applied to a distal portion of the shaft increases the frictional forces.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority of European patent applicationNo. 08 000 033.4 filed on Jan. 3, 2008.

BACKGROUND OF THE INVENTION

The invention relates to a shaft rotating device for rotating a shaft ofa medical instrument about its longitudinal axis relative to a handle ofthe medical instrument.

The invention further relates to a medical instrument for endoscopicsurgery, comprising a shaft and a handle, wherein the handle is arrangedat a proximal portion of the shaft.

A shaft rotating device is, for example, known from the firm catalogueof Karl Storz GmbH & Co., Tuttlingen, “Karl Storz—Endoskope,Laparoskopie”, 5. edition 1/2005, page SCC-INTRO 5B. This brochure showsa handle for the laparoscopy with the product number 33131 or 30131which comprises the known shaft rotating device.

The medical instrument comprising the known shaft rotating device isused for endoscopic operations in the field of the minimally invasivesurgery, during which abnormal tissue of e.g. the appendix, the bladderetc. is removed. The present invention, however, is not limited to a useof the shaft rotating device in such a medical instrument.

The known medical instrument comprises an elongated hollow shaft, atwhose proximal portion a handle for operation by the surgeon isarranged. A distal portion of the shaft is introduced into a cavity of apatient during the operation, at which jaws are pivotably arranged forgrasping and/or cutting tissue. At least one jaw is in drivingconnection with the handle via a thin pull/push rod for controlling itsgrasping and/or cutting capability. At the proximal portion of the shafta shaft rotating device is arranged, which allows the shaft rotatingabout its longitudinal axis relative to the handle. Upon rotating theshaft, the position of the jaws relative to the tissue can be adapted inthe best way regarding the requirements of the operation.

The proximal portion of the shaft is rotationally fixedly accommodatedin an opening of the handle. As an outer diameter of the shaft isslightly larger than an inner diameter of the opening, an outer surfaceof the shaft and an inner surface of the handle are in frictionalcontact. The known shaft rotation device further comprises an operatingelement being rotationally fixed at the shaft. Upon operating theoperating element, the surgeon can rotate the shaft relative to thehandle by a small angular range against the frictional forces. In turn,when outer forces affect the distal portion of the shaft during theoperation, an undesired rotation of the shaft relative to the handle isprevented due to the large frictional forces between the surfaces of theshaft and the handle.

It is a disadvantage of the known shaft rotating device, that largefrictional forces are required to fix the shaft rotationally stationarywith respect to the handle during the operation. For rotating the shaftrelative to the handle, these frictional forces have to be overcome,which requires a large torque applied to the operating element duringthe shaft of the medical instrument being introduced into the bodycavity. This aggravates the handling of the instrument and increases therisk of injuries for the patient during the operation.

Furthermore, it is disadvantageous, that the strength of the torqueapplied to the operating element depends on the frictional forcesbetween the surfaces of the shaft and the handle. In case of smallproduction variations regarding e.g. the materials and dimensions of theshaft and the handle, a torque with a different strength has to beexerted by the surgeon on the operating element. Therefore using such amedical instrument requires the surgeon not only to be experienced withthis medical instrument, but also to adapt himself to a medicalinstrument with a shaft rotating device having slightly differentfrictional forces.

Moreover, the known shaft rotating device has the drawback, thatrotating the shaft against the frictional forces requires a hugephysical effort by the surgeon during the operation. The operation isthus physically exhausting for the surgeon, which increases thepossibility of unintentional malpractices of the surgeon.

A further disadvantage of the known shaft rotating device is, that anyrotation of the shaft relative to the handle mechanically affects thesurfaces of the involved components in terms of polishing them, so thatthese surfaces turn smooth. As a result, the frictional forces betweenthe shaft and the handle can decrease to an extent that the shaft canrotate in undesired fashion, when small external torques are applied tothe shaft.

SUMMARY OF THE INVENTION

Therefore it is an object of the present invention to improve both theshaft rotating device and the medical instrument of the kinds mentionedat the outset, so that the medical instrument can be easily operated bythe surgeon during the operation without large physical effort.

According to an aspect of the invention, a shaft rotating device forrotating a shaft of a medical instrument about a longitudinal axis ofthe shaft relative to a handle of the medical instrument is provided,comprising an operating element for rotating the shaft, which isarranged at a proximal portion of the shaft and which is in drivingconnection with the shaft such that the shaft is rotatable relative tothe handle against frictional forces, a frictional element having afirst surface, wherein the first surface of the frictional element is infrictional contact with a second surface of a counterpart for keepingthe shaft and the handle rotationally stationary with respect to eachother and movable against the frictional forces,

the operating element and the frictional element being in operationalconnection with respect to one another such that a torque applied to theoperating element decreases the frictional forces, and the shaft and thefrictional element being in operational connection with one another suchthat a torque applied to a distal portion of the shaft increases thefrictional forces.

According to another aspect of the invention, a medical instrument forendoscopic surgery is provided, comprising a shaft having a proximalportion and a longitudinal axis, a handle arranged at the proximalportion of the shaft, a shaft rotating device, the shaft rotating devicecomprising an operating element for rotating the shaft, which isarranged at a proximal portion of the shaft and which is in drivingconnection with the shaft such that the shaft is rotatable relative tothe handle against frictional forces, a frictional element having afirst surface, wherein the first surface of the frictional element is infrictional contact with a second surface of a counterpart for keepingthe shaft and the handle rotationally stationary with respect to eachother and movable against the frictional forces, the operating elementand the frictional element being in operational connection with respectto one another such that a torque applied to the operating elementdecreases the frictional forces, and the shaft and the frictionalelement being in operational connection with one another such that atorque applied to a distal portion of the shaft increases the frictionalforces.

The shaft rotating device of the medical instrument comprises africtional element, whose surface is in frictional contact with asurface of a counterpart. This arrangement of the two elements providesthe frictional forces, so that the shaft and the handle are rotationallystationary with respect to each other. In addition, when applying atorque to the operating element, the frictional forces are decreasedsuch that the shaft is easily rotatable relative to the handle withoutincreased physical effort. In turn, applying a torque to the distalportion of the shaft results in an increase of the frictional forcessuch that the shaft and the handle are not rotatable relative to eachother. The shaft rotating device is thus based on a very easy mechanismthat advantageously provides variable frictional forces regarding theexternally applied torques, which enables on the one hand a rotationallyfixed arrangement of the shaft and the handle when rotation is notdesired and on the other hand a rotation of the shaft relative to thehandle without large physical effort, when rotation is desired.

This means in the latter case that the surgeon only needs to exert asmall torque on the operating element for rotating the shaft relative tothe handle, as the frictional forces are reduced upon operating theoperating element.

It is a further advantage of the shaft rotating device according to theinvention, that the shaft and the handle are not in direct connectionwith one another, thereby both elements being not damaged due toabrasion of their surfaces.

In a preferred embodiment of the invention, the frictional forces are,when applying the torque to the distal portion of the shaft, increasedin that the surface of the frictional element is pressed on the surfaceof the counterpart.

This way of locking the shaft relative to the handle is very easy in thesense that no further technical means are required for increasing thefrictional forces. Therefore production costs of the shaft rotatingdevice and thus the medical instrument are advantageously lower comparedto shaft rotating devices comprising more complicated shaft rotatingmechanisms.

In a further preferred embodiment of the invention, the frictionalforces are, when applying the torque to the operating element, decreasedin that the surface of the frictional element is at least partiallyreleased from the surface of the counterpart.

This rotating mechanism advantageously allows a very fast and flexibleway to rotate the shaft relative to the handle. In addition, the surgeondoes not need to apply a large torque to the operating element in orderto rotate the shaft, so that the medical instrument can be used inone-hand-operation.

In a further preferred embodiment of the invention, the shaft rotatingdevice further comprises a rotation transmission element which is inrotationally fixed connection with the frictional element fortransmitting the torque applied to the distal portion of the shaft tothe frictional element.

Here, the rotation transmission element mediates the torque exerted onthe distal portion of the shaft to the frictional element due to therotationally fixed connection of both components, whereby the frictionalforces are increased for locking the shaft relative to the handle.Therefore, the frictional element can be advantageously designed to bevery small, as the frictional element has not to be in direct connectionwith the distal portion of the shaft for applying torque to it.

In a further preferred embodiment of the invention, the rotationtransmission element is in rotationally fixed connection with theoperating element via the frictional element for transmitting the torqueapplied to the operating element to the frictional element.

In this context, these three components of the shaft rotation devicefunction together to mediate the torque applied to the operating elementto the frictional element, whereby the shaft is rotated relative to thehandle. Advantageously, the rotation transmission element accomplishestwo different functions, so that further components for the rotatingmechanism are obsolete and production costs of the shaft rotating deviceaccording to the invention are lower compared to more complicated shaftrotating devices.

In a further preferred embodiment of the invention, the rotationtransmission element is, when seen in a radial direction, arrangedbetween the frictional element and the operating element.

Arranging the rotation transmission element in such a way offers an easyway for connecting this element in a rotationally fixed way with boththe frictional element and the operating element. In this way, thisarrangement of the three components advantageously provides a compactdesign of the shaft rotating device.

In a further preferred embodiment of the invention, the rotationtransmission element is slightly spaced from the frictional element.

The advantage here is that no further frictional forces are providedbetween the rotation transmission element and the frictional element,which could hamper the movement of the shaft relative to the handle whenrotation of the shaft relative to the handle is desired. In addition, adamage of both the rotation transmission element and the frictionalelement is thus prevented, thereby advantageously saving repairing costsfor the shaft rotating device and the medical instrument.

In a further preferred embodiment of the invention, the rotationtransmission element is slightly spaced from the operating element.

In this context, no further frictional forces are provided between thesurfaces of the rotation transmission element and the operating element,thereby advantageously facilitating the movement of the shaft relativeto the handle. Furthermore, a damage of both components is prevented, sothat no repairing costs for the rotation trans-mission element areincurred.

In a further preferred embodiment of the invention, the rotationtransmission element is rotationally fixed to the shaft.

Arranging the rotation transmission element rotationally fixed to theshaft advantageously provides the constructively easiest way fortransferring the torque applied to the distal portion of the shaft tothe frictional element which then blocks rotation of the shaft relativeto the handle.

In a further preferred embodiment of the invention, the counterpart isrotationally fixed to the handle.

The advantage of this measure is, that this design of the shaft rotatingdevice guarantees the shaft and the handle being movable relative to oneanother.

In a further preferred embodiment of the invention, the surface of thefrictional element circumferentially lies on top of the surface of thecounterpart.

This arrangement of the frictional element and the counterpartadvantageously enables larger frictional forces compared to anarrangement, where the frictional element is in contact with e.g. onlyfew portions of the counterelement. Thus sufficiently large frictionalforces are provided for keeping the shaft rotationally stationary withrespect to the handle when rotation is undesired.

In a further preferred embodiment of the invention, the operatingelement is a rotating wheel.

The advantage here is, that a rotating wheel can be easily grasped bythe surgeon. In addition, a rotating wheel advantageously allows arotation of the shaft relative to the handle by an angular range of360°.

In a further preferred embodiment of the invention, the frictionalelement is a first and second torsion spring, which are wound in acounter-rotating way with respect to one another and which are arrangedaround the surface of the counterpart along the longitudinal axis of theshaft.

Two torsion springs advantageously represent a constructively easydesign of the frictional element, where the frictional forces areprovided between the inner surface of the two springs and the outersurface of the counterelement. Moreover, this arrangement of the springswith windings transverse to the longitudinal axis of the shaftadvantageously offers the possibility to press the springs tightlyagainst the surface of the counterpart and release them from it,respectively. It also provides a stable design of the shaft rotatingdevice, as the frictional element cannot be moved or tilted along theshaft extension.

In a further preferred embodiment of the invention, the rotationtransmission element is a slotted tube comprising slits, wherein firstand second end portions of the first and second springs outwardly extendin an essentially radial fashion and engage into the slits.

This design of the rotation transmission element and the frictionalelement advantageously provides the rotationally fixed connection ofboth components, as any rotation of the transmission element is directlytransferred to the frictional element via a leverage effect of the firstand second end portions of the first and second springs on the slottedtube.

In a further preferred embodiment of the invention, the first endportions of the first and second springs being opposite to one anotherare arranged next to one another and accommodated within a first slit ofthe slotted tube.

In this context, the two springs are arranged in such a way that thefirst end portions of the first and second springs are adjacent to oneanother. The rotationally fixed connection of the frictional element andthe rotation transmission element, i.e. of the first and second springsand the slotted tube, is achieved by the first end portions of the firstand second springs engaging into the first slit. When applying a torqueto the distal portion of the shaft, a side wall of the first slitpresses against the first end portion of that spring which is woundedagainst the rotational sense of the applied torque, in order to pressthe surface of this spring closer to the surface of the counterpart.This mechanism advantageously enables locking the shaft relative to thehandle independently of the rotational sense of the applied torque.

In a further preferred embodiment of the invention, the rotating wheelcomprises recesses for accommodating the second end portions of thefirst and second springs.

This design of the shaft rotating device causes the second end portionsof the first and second springs to engage into the recesses of therotating wheel for creating the rotationally fixed connection of thefrictional element, the rotation transmission element and the rotatingwheel. When applying a torque to the rotating wheel, the side wall ofthe second or third slits presses against the second end portion of thatspring being wound in the rotational sense of the applied torque forreleasing the surface of this spring from the surface of thecounterpart. In this way, the shaft is advantageously rotatable relativeto the handle in both direction senses when rotation is desired.

In a further preferred embodiment of the invention, the first endportions of the first and second springs do not have play in the firstslit.

In this context, this arrangement of the first end portions of the firstand second springs in the first slit of the slotted tube causes thesurface of that spring whose first end portion is pressed against to beimmediately pressed tighter against the surface of the counterpart. Thisleads to a direct transfer of the torque applied to the distal portionof the shaft to the frictional element, thereby advantageouslypreventing any rotation of the shaft relative to the handle even by asmall angular range when rotation of the shaft relative to the handle isundesired.

In a further preferred embodiment of the invention, the second endportions of the first and second springs have play in second and thirdslits of the slotted tube.

The advantage of this measure is, that an unintentional rotation of theoperating element does not immediately result in a rotation of the shaftrelative to the handle.

In a further preferred embodiment of the invention, the first and secondsprings comprise at least two turns.

Designing the springs with at least two turns advantageously providesenough contact surface of the first and second springs, i.e. of thefrictional element, with respect to the surface of the counterpart forcreating sufficiently large frictional forces. In addition, tilting ofthe first and second springs towards the longitudinal extension of theshaft is prevented, as two circumferentially windings of the springsform a very stable arrangement.

In a further preferred embodiment of the invention, an inner diameter ofthe first and second springs is by approximately 0.5% to 2.0%,preferably by approximately 1%, smaller than an outer diameter of thecounterpart.

In this context, these diameters of both components evoke the frictionalforces between the involved surfaces, as the first and second springstightly fit on the outer surface of the counterpart. Therefore anyrelative movement of the shaft and the handle is advantageouslyprevented.

Further advantages will be apparent from the following description andthe accompanying drawings. It is to be understood that theafore-mentioned features and those to be explained below are not onlyapplicable in the combinations given, but also in other combinations orin isolation without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is illustrated in the drawingsand will be described hereinafter with reference thereto. In thedrawings:

FIG. 1 is a schematic view of a medical instrument comprising a shaftrotating device in accordance with the invention;

FIG. 2A is a perspective view of a proximal portion of the shaft of theinstrument in FIG. 1, at which a slotted tube and first and secondsprings are arranged;

FIG. 2B is a further perspective view of the proximal portion of theshaft in FIG. 2A without the first and second springs;

FIG. 3A is a cross sectional view of the first and second springs inFIG. 2A;

FIG. 3B is a perspective view of the first and second springs in FIG.3A;

FIG. 4 is a perspective view of the counterpart of the handle, on whichthe first and second springs in FIG. 3A are arranged; and

FIG. 5 is a cross sectional view of the rotating wheel, the slotted tubeand the first and second springs.

DETAILED DESCRIPTION OF A PREFERRED EXEMPLARY EMBODIMENT

FIG. 1 shows, in a schematic representation, a shaft rotating devicegenerally labelled with reference numeral 10 as part of a medicalinstrument 12. The shaft rotating device 10 is used for rotating anelongated hollow shaft 14 of the medical instrument 12 with respect to ahandle 16 of the medical instrument 12 about a longitudinal axis 18 ofthe shaft 14. Further details of the shaft rotating device 10 are shownin FIGS. 2A through 5.

Preferably, the medical instrument 12 is made of steel to be easilycleaned after being used.

During an operation a distal portion 20 of the shaft 14 is introducedinto a body cavity of a patient for e.g. grasping and/or cutting tissuee.g. of the appendix. Jaws 22, which are pivotably arranged at thedistal portion 20 of the shaft 14, are connected with the handle 16 viaan axially movable force transmission mechanism (not shown) such as apush/pull rod. Upon rotating the shaft 14 relative to the handle 16, thejaws 22 are rotated for arranging them in the most convenient positionwith respect to the tissue and thus improving their grasping and/orcutting capabilities during the operation.

The shaft rotating device 10 comprises an operating element 24, here arotating wheel 26, for rotating the shaft 14 relative to the handle 16.The rotating wheel 26 is arranged at a proximal portion 28 of the shaft14. Moreover, it is in driving connection with the shaft 14 such thatthe shaft 14 is rotatable relative to the handle 16 against frictionalforces. The design of the rotating wheel 26 allows a rotation of theshaft 14 by an angular range of 360° in both rotation senses. Forfacilitating its usage, the rotating wheel 26 comprises grooves 29 whichrun in an essentially parallel way with respect to the extension of theshaft 14. The rotating wheel 26 is made of steel. However, it can alsobe made of a light material such as teflon.

As shown in FIG. 2A, the shaft rotating device 10 further comprises africtional element 30 and a rotation transmission element 32.

The frictional element 30 comprises a surface 34 which is in frictionalcontact with a surface 36 of a counterpart 38 for providing thefrictional forces between both components. Here, the counterpart 38 isrotationally fixed to the handle 16. In this way, these frictionalforces oppose any movement of the shaft 14 relative to the handle 16 forkeeping both the handle 16 and the shaft 14 rotationally stationary withrespect to each other.

In addition, the frictional element 30 and the rotating wheel 26 are inoperational connection with respect to one another such that a torqueexternally applied to the rotating wheel 26 by a surgeon decreases thefrictional forces between the surfaces 34, 36 of the frictional element30 and the counterpart 38. In turn, the frictional forces between bothcomponents are increased for locking the shaft 14 with respect to thehandle 16, when a torque is applied to the distal portion 20 of theshaft 14 during the operation. Such a torque may be caused by theinteraction between the jaws 22 and the tissue to be treated. In orderto enable the latter effect, the shaft 14 and the frictional element 30are in operational connection.

The rotation transmission element 32 is rotationally fixed to theproximal portion 28 of the shaft 14. It is further in rotationally fixedconnection with the frictional element 30, in order to transmit thetorque applied to the distal portion 20 of the shaft 14 to thefrictional element 30. A further rotationally fixed connection of therotation transmission element 32 and the rotating wheel 26 via thefrictional element 30 enables mediating the torque applied to therotating wheel 26 to the frictional element 30. When seen in a radialway, the rotation transmission element 32 is further arranged betweenthe frictional element 30 and the rotating wheel 26 leading to a verycompact design of the shaft rotating device 10 (see FIG. 5).

As shown in FIGS. 2A, 2B, the frictional element 30 is designed as firstand second springs 40, 42, whose windings are counter-rotating withrespect to one another. The first and second springs 40, 42 are arrangedalong the longitudinal axis 18 of the shaft 14 in such a way that theirwindings are transverse with respect to the longitudinal axis 18 of theshaft 14. Thus the surface 34 of the frictional element 30 correspondingto an inner surface 44 of the first and second spring 40, 42circumferentially lies on top on the surface 36 of the counterpart 38providing sufficiently large frictional forces for keeping the shaft 14rotationally stationary with respect to the handle 16.

The first and second springs 40, 42 are identically designed andcomprise at least two turns, here exactly two turns. They are made ofsteel for providing enough rigidity of their rotationally fixedconnection to the operating element 24 and the rotation transmissionelement 32.

The counterpart 36 is designed as a collar 46 made of steel which isrotationally fixed to the handle 16. As it is shown in FIG. 4, thecollar 46 projects from the handle 16 by an angle of almost 90°, so thata proximal end portion (not shown) of the shaft 14 is rotationallyaccommodated in the collar 46. The collar 46 and the handle 16 aredesigned as distinct components, however, both can be also formed in asingle-pieced or monolithic way.

For providing the frictional forces, an inner diameter 48 of the firstand second springs 40, 42 is by approximately 0.5% to 2.0%, preferablyby approximately 1%, smaller than an outer diameter 50 of the collar 46.In this way, the first and second springs 40, 42 fit tightly around asurface 51 of the collar 46, whereby the first and second springs 40, 42are rigidly held on the surface 51 of the collar 46.

The rotation transmission element 32 is designed as a slotted tube 52,e.g. made of steel which is arranged in an parallel way with respect tothe longitudinal axis 18 of the shaft 14. The slotted tube 52 comprisesa first, second and third slit 54-58, which are formed within aperipherical wall 59 of the slotted tube 52 in an essentially parallelway with respect the longitudinal axis 18 of the shaft 14. They extendfrom a first front side 60 being open and arranged near the handle 16 toapproximately ⅔ of a tube extension. A second front side 62 is formedring-like, where an inner diameter of an opening 64 of the second frontside 62 approximately coincides with an outer diameter 66 of the shaft14. In order to rotationally fix the slotted tube 52 to the shaft 14,the ring opening 64 is welded to the shaft 14. However, the shaft 14 andthe slotted tube 52 can be also designed in a single-pieced way.

Furthermore, an inner diameter 68 of the slotted tube 52 is slightlylarger than an outer diameter 70 of the first and second springs 40, 42,so that the tube 52 is slightly spaced from the first and the secondsprings 40, 42. In this way, no further frictional forces are providedbetween both components, which could negatively affect the rotation ofthe shaft 14 relative to the handle 16 in the sense that furtherfrictional forces are provided which have to be overcome when thesurgeon wishes to rotate the shaft. Additionally, an outer diameter 72of the tube 52 is slightly smaller than an inner diameter 74 of therotating wheel 26, so that both components are slightly spaced from eachother. Therefore, no additional frictional forces are provided betweenthese two components for allowing an easy and flexible operatingmechanism of the rotating wheel 26. Depending on the material of theslotted tube 52 a wall thickness 76 of the tube 52 is dimensioned insuch a way, that it provides enough rigidity against external forcesexerted on it.

Side walls 78, 80 of the first slit 54 are designed in such a way thatthey run in an almost parallel way respecting each other and thelongitudinal axis 18 of the shaft 14. In contrast, the second and thirdslits 56, 58 broaden towards the first and second springs 40, 44, sothat side walls 82-88 of the second and third slits 56, 58 are notparallelly formed to each other.

The first and second springs 40, 42 comprise first and second endportions 90-96, which outwardly extend in an essentially radial way, sothat the first and second end portions 90-96 of the first and secondsprings 40, 42 engage into the slits 54-58. The opposite first endportions 90, 92 of the first and second springs 40, 42 are arrangeddirectly next to one another, whereas the second end portions 94, 96 ofeach spring 40, 42 are arranged by an angle of approximately 45°respecting the associated first end portions 90, 92.

As shown in FIG. 3B, the first and second springs 40, 42 comprise twoturns of 360° and one turn of 315°, so that the second end portions 94,96 are arranged in front of the first end portions 90, 92, when seen inthe winding sense of the first and second springs 40, 42. It is alsopossible, that the first and second springs 40, 42 comprise three turnsof 360° and one of 45°, so that the second end portions 94, 96 arearranged behind the first end portions 90, 92, when seen in the windingsense of the first and second springs 40, 42.

A length 98 of the first end portions 90, 92 is smaller than a length100 of the second end portions 94, 96. Therefore the first end portions90, 92 are accommodated in the first slit 54 of the slotted tube 52,whereas the longer second end portions 94, 96 extend through the secondand third slits 56, 58, respectively.

As shown in FIG. 5, the rotating wheel 26 comprises two recesses 102,104, in which the second end portions 94, 96 of the first and secondsprings 40, 42 are received.

The first and second end portions 90-96 thus provide the rotationallyfixed connection of the slotted tube 52 to the first and second springs40, 42 and the rotating wheel 26, respectively.

In order to rotate the shaft 14 relative to the handle 16 or to keepboth components rotationally stationary with respect to each other, thefrictional forces between the first and second springs 40, 42 and thecollar 46 are, as mentioned above, variable, i.e. they can be decreasedor increased, respectively. The frictional forces are decreased by atleast partially releasing the inner surface 44 of the first and secondsprings 40, 42, i.e. the surface 34 of the frictional elements 30, fromthe surface 51 of the collar 46, i.e. from the surface 36 of thecounterpart 38. In addition, the frictional forces are increased in sucha way that the inner surface 44 of the first and second springs 40, 42,i.e. the surface 34 of the frictional elements 30, is pressed onto thesurface 51 of the collar 46, i.e. onto the surface 36 of the counterpart38.

When applying a torque to the rotating wheel 26 in order to rotate theshaft 14, for example clockwise with respect to FIG. 5, side walls 108,112 of the recesses 102, 104, which are arranged in counter-rotationalsense, press against both second end portions 94, 96 of the first andsecond springs 40, 42. As the second end portions 94, 96 of the firstand second springs 40, 42 have play in the second and third slits 56,58, the rotating wheel 26 is first rotated by a small angular range,until the second end portion 94 of the first spring 40, being wound inthe rotational sense of the applied torque, is pressed tighter onto theside wall 82 of the corresponding second slit 56. A portion 114 of thefirst spring 40 is released from the surface 51 of the collar 46, as theside wall 82 of the corresponding second slit 56 broadens towards thewindings of the first and second springs 40, 42. Thus the frictionalforces between the first spring 40 and the collar 46 are decreased. Theslotted tube 52 and thus the shaft 14 move in the rotation sense of therotating wheel 26. The second end portion 96 of the second spring 42being wound in counter-rotational sense does not come into contact withthe side wall 88 of the third slit 58, so that a portion 116 of thesecond spring 42 is not pressed tighter onto the surface 36 of thecollar 46, whereby the frictional forces between the second spring 42and the collar 46 are not increased and the clockwise rotation of thefirst and second springs 40, 42 is not affected. When changing therotation sense of the rotating wheel 26, the corresponding functionapplies.

When a torque is applied to the distal portion 20 of the shaft 14, forexample clockwise with respect to FIG. 5, the shaft 14 remainsrotationally stationary with respect to the handle 16. As the first endportions 90, 92 of the first and second springs 40, 42 do not have playin the first slit 54, the side wall 80 of the first slit 54 isimmediately pressed against both the first end portions 90, 92 of thefirst end second springs 40, 42. The parallel shape of the side walls78, 80 causes a portion 118 of first spring 40 to be pressed tighteronto the surface 51 of the collar 46, whereas a portion 120 of thesecond spring 42 is not released from the surface 51 of the collar 46.Furthermore, the second end portions 94, 96 of the first and secondsprings 40, 42 do not come into contact with the side walls 82-88 of thesecond and third slits 56, 58, as the second end portions 94, 96 haveplay in them. Therefore the frictional forces 10 are increased and theshaft 14 is kept rotationally stationary with respect to the handle 16.According to an identical design of the first and second springs 40, 42,the shaft 14 is also unmovable relative to the handle 16 when a torqueis applied anti-clockwise to the distal portion 20 of the shaft 14.

1. A shaft rotating device for rotating a shaft of a medical instrumentabout a longitudinal axis of said shaft relative to a handle of saidmedical instrument, comprising an operating element for rotating saidshaft, which is arranged at a proximal portion of said shaft and whichis in driving connection with said shaft such that said shaft isrotatable relative to said handle against frictional forces, africtional element having a first surface, wherein said first surface ofsaid frictional element is in frictional contact with a second surfaceof a counterpart for keeping said shaft and said handle rotationallystationary with respect to each other and movable against saidfrictional forces, said operating element and said frictional elementbeing in operational connection with respect to one another such that atorque applied to said operating element decreases said frictionalforces, and said shaft and said frictional element being in operationalconnection with one another such that a torque applied to a distalportion of said shaft increases said frictional forces.
 2. The shaftrotating device of claim 1, wherein, when applying said torque to saiddistal portion of said shaft, said frictional forces are increased inthat said first surface of said frictional element is pressed on saidsecond surface of said counterpart.
 3. The shaft rotating device ofclaim 1, wherein, when applying said torque to said operating element,said frictional forces are decreased in that said first surface of saidfrictional element is released at least partially from said secondsurface of said counterpart.
 4. The shaft rotating device of claim 1,further comprising a rotation transmission element which is inrotationally fixed connection with said frictional element fortransmitting said torque applied to said distal portion of said shaft tosaid frictional element.
 5. The shaft rotating device of claim 4,wherein said rotation transmission element is in rotationally fixedconnection with said operating element via said frictional element fortransmitting said torque applied to said operating element to saidfrictional element.
 6. The shaft rotating device of claim 4, wherein,when seen in a radial direction, said rotation transmission element isarranged between said frictional element and said operating element. 7.The shaft rotation device of claim 4, wherein said rotation transmissionelement is slightly spaced from said frictional element.
 8. The shaftrotation device of claim 7, wherein said rotation transmission elementis slightly spaced from said operating element.
 9. The shaft rotationelement of claim 4, wherein said rotation transmission element isrotationally fixed to said shaft.
 10. The shaft rotating device of claim1, wherein said counterpart is rotationally fixed to said handle. 11.The shaft rotating device of claim 1, wherein said first surface of saidfrictional element circumferentially lies on top of said second surfaceof said counterpart.
 12. The shaft rotating device of claim 1, whereinsaid operating element is a rotating wheel.
 13. The shaft rotatingdevice of claim 1, wherein said frictional element has a first and asecond torsion spring, which are wound in a counter-rotating way withrespect to one another and which are arranged around said second surfaceof said counterpart along a longitudinal axis of said shaft.
 14. Theshaft rotating device of claim 4, wherein said rotation transmissionelement has a slotted tube comprising slits, wherein first and secondend portions of said first and second torsion springs outwardly extendin an essentially radial fashion and engage into said slits.
 15. Theshaft rotating device of claim 14, wherein said first end portions ofsaid first and second torsion springs being opposite to one another arearranged next to one another and accommodated within a first slit ofsaid slits of said slotted tube.
 16. The shaft rotating device of claim15, wherein said operating element is a rotating wheel, and saidrotating wheel comprises recesses for accommodating said second endportions of said first and second torsion springs.
 17. The shaftrotating device of claim 14, wherein said first end portions of saidfirst and second torsion springs do not have play in a first slit ofsaid slits of said slotted tube.
 18. The shaft rotating device of claim14, wherein said second end portions of said first and second torsionsprings have play in second and third slits of said slits of saidslotted tube.
 19. The shaft rotating device of claim 13, wherein saidfirst and second torsion springs have at least two turns.
 20. The shaftrotating device of claim 13, wherein an inner diameter of said first andsecond torsion springs is by approximately 0.5% to 2.0% smaller than anouter diameter of said counterpart.
 21. A medical instrument forendoscopic surgery, comprising a shaft having a proximal portion and alongitudinal axis, a handle arranged at said proximal portion of saidshaft, a shaft rotating device, said shaft rotating device comprising anoperating element for rotating said shaft, which is arranged at aproximal portion of said shaft and which is in driving connection withsaid shaft such that said shaft is rotatable relative to said handleagainst frictional forces, a frictional element having a first surface,wherein said first surface of said frictional element is in frictionalcontact with a second surface of a counterpart for keeping said shaftand said handle rotationally stationary with respect to each other andmovable against said frictional forces, said operating element and saidfrictional element being in operational connection with respect to oneanother such that a torque applied to said operating element decreasessaid frictional forces, and said shaft and said frictional element beingin operational connection with one another such that a torque applied toa distal portion of said shaft increases said frictional forces.